拌制工艺对NCM开裂性能影响试验研究

Experimental study on influence of mixing process on cracking performance of nano-clay cement mortar

为了研究拌制工艺对纳米黏土水泥砂浆(NCM)抗裂性能的影响,选用4种不同粒径纳米黏土,通过超声分散试验研究了纳米黏土在水中分散性,采用平板刀口约束试验,研究了3种拌制工艺下NCM早期开裂过程,基于分形理论揭示了NCM表面裂缝的分布特性,建立了分形维数与不同拌制工艺下NCM开裂程度关系。研究结果表明:纳米黏土悬浊液沉降速率越小,分散后团聚颗粒粒径越小,水中分散性也越好;工艺A中NCM抗裂性能较工艺B、C好,其中,龄期为1、7 d时,NMK-4开裂程度较普通水泥砂浆分别降低100%、91%(工艺A),85%、80%(工艺B),92%、88%(工艺C);同种纳米黏土中,工艺B的NCM表面裂缝分形维数及其增长率最大,工艺A的NCM平板表面裂缝分形维数及其增长率最小;分形维数较小,其抗裂性越好。

To investigate the effect of mixing process on the anti-cracking of nano-clay cement mortar(NCM),four different particle size nano-clay were selected,and the dispersibility of nano-clay in water was studied by ultrasonic dispersion test.The early cracking process of NCM under three mixing processes was examined using the flat test.Based on the fractal theory,the cracking distribution characteristics on the surface of NCM were analyzed,and the relationship between fractal dimension and NCM cracking degree under different mixing processes were established.It is shown that the smaller the sedimentation rate of the nanoclay suspension,the smaller the particle size of the agglomerated particles after dispersion and the better the dispersibility in water.The anti-cracking of NCM in process A is better than that of process B and C.When the age is 1,7 d,compared with the common mortar,the degree of cracking of NMK-4 decreased by 100%,91%(process A),85%,80%(process B),92%,88%(process C)respectively.In the same kind of nanoclay,the crack fractal dimension of NCM and its growth rate are the largest in process B,but they are the smallest in process A.The fractal dimension is smaller,and the crack resistance is better.